Papers by Fernando Xavier
New Journal of Chemistry
The iron complex converted higher amounts of substrates while the copper complex presented higher... more The iron complex converted higher amounts of substrates while the copper complex presented higher selectivity toward selected products.
Managerial Auditing Journal, 2002
This paper revisits a typical bricks and mortar company that had successfully applied strategy de... more This paper revisits a typical bricks and mortar company that had successfully applied strategy development and deployment methodologies such as Hoshin and QFD to their transformation process. With the explosive growth of the Internet, and the increasingly turbulent economic environment, the viability of current business models is threatened. In the process, it is calling into question the methodologies that worked
International Journal of Quality & Reliability Management, 2003
Introduced to the West from Japan, Quality Function Deployment (QFD) is a powerful approach to cu... more Introduced to the West from Japan, Quality Function Deployment (QFD) is a powerful approach to customer-focused product development. In recent years, many practitioners and academics have recognized the potential of these methods and applied them to strategic formulation and decision making as well. Earlier reviews of the documented accounts of QFD-based approaches to strategy have been presented at the 7th
Managerial Auditing Journal, 2002
This paper revisits a typical bricks and mortar company that had successfully applied strategy de... more This paper revisits a typical bricks and mortar company that had successfully applied strategy development and deployment methodologies such as Hoshin and QFD to their transformation process. With the explosive growth of the Internet, and the increasingly turbulent ...
International Journal of Quality & Reliability Management, 2003
Introduced to the West from Japan, Quality Function Deployment (QFD) is a powerful approach to cu... more Introduced to the West from Japan, Quality Function Deployment (QFD) is a powerful approach to customer-focused product development. In recent years, many practitioners and academics have recognized the potential of these methods and applied them to strategic formulation ...
A amina macrocíclica 1,4,7-trimetil-1,4,7triazaciclononano (Me 3 TACN) é um ligante com forte ten... more A amina macrocíclica 1,4,7-trimetil-1,4,7triazaciclononano (Me 3 TACN) é um ligante com forte tendência de coordenação facial, o que promove estabilização de diversos motivos estruturais inorgânicos e bioinorgânicos. No entretanto, sua síntese é extremamente trabalhosa e dispendiosa em termos de tempo de reação e custos financeiros. Recentemente, Jovito e colaboradores reportaram o emprego do ligante Me 3 AAZ como uma molécula alternativa viável no sentido de mimetizar as, já bem conhecidas, propriedades do Me 3 TACN uma vez que a síntese do Me 3 AAZ é mais simples e apresenta baixos custos se comparada ao clássico macrociclo. Neste trabalho apresenta-se a síntese e estrutura cristalina de um novo complexo mononuclear com unidade estrutural [Cu II (Me 3 AAZ) 2 ]Cl 2 .2H 2 O ( 1), buscando investigar as propriedades do ligante Me 3 AAZ como um potencial mimético para o Me 3 TACN.
Journal of Inorganic Biochemistry, 2006
The new homodinuclear complexes, ½Cu II 2 ðHLdtbÞðl-OCH 3 ÞðClO 4 Þ 2 (1) and ½Cu II 2 ðLdtbÞðl-O... more The new homodinuclear complexes, ½Cu II 2 ðHLdtbÞðl-OCH 3 ÞðClO 4 Þ 2 (1) and ½Cu II 2 ðLdtbÞðl-OCH 3 ÞðBPh 4 Þ (2), with the unsymmetrical N 5 O 2 donor ligand (H 2 Ldtb) -{2-[N,N-Bis(2-pyridylmethyl)aminomethyl]-6-[N 0 ,N 0 -(3,5-di-tert-butylbenzyl-2-hydroxy)(2-pyridylmethyl)]aminomethyl}-4-methylphenol have been synthesized and characterized in the solid state by X-ray crystallography.In both cases the structure reveals that the complexes have a common {Cu II (l-phenoxo)(l-OCH 3 )Cu II } structural unit.Magnetic susceptibility studies of 1 and 2 reveal J values of À38.3 cm À1 and À2.02 cm À1 , respectively, and that the degree of antiferromagnetic coupling is strongly dependent on the coordination geometries of the copper centers within the dinuclear {Cu II (l-OCH 3 )(l-phenolate)Cu II } structural unit.Solution studies in dichloromethane, using UV-Visible spectroscopy and electrochemistry, indicate that under these experimental conditions the first coordination spheres of the Cu II centers are maintained as observed in the solid state structures, and that both forms can be brought into equilibrium ([Cu 2 (HLdtb)(l-OCH 3 )] 2+ = [Cu 2 (Ldtb)(l-OCH 3 )] + + H + ) by adjusting the pH with Et 3 N (Ldtb 2À is the deprotonated form of the ligand).On the other hand, potentiometric titration studies of 1 in an ethanol/water mixture (70:30 V/V; I = 0.1 M KCl) show three titrable protons, indicating the dissociation of the bridging CH 3 O À group.The catecholase activity of 1 and 2 in methanol/water buffer (30:1 V/V) demonstrates that the deprotonated form is the active species in the oxidation of 3,5di-tert-butylcatechol and that the reaction follows Michaelis-Menten behavior with k cat = 5.33 · 10 À3 s À1 and K M = 3.96 · 10 À3 M. Interestingly, 2 can be electrochemically oxidized with E 1/2 = 0.27 V vs.Fc + /Fc (Fc + /Fc is the redox pair ferrocinium/ferrocene), a redox potential which is believed to be related to the formation of a phenoxyl radical.Since these complexes are redox active species, we analyzed their activity toward the nucleic acid DNA, a macromolecule prone to oxidative damage.Interestingly these complexes promoted DNA cleavage following an oxygen dependent pathway.
Inorganic Chemistry, 2005
The structure and physicochemistry of the [Ni(II)(AAZ)(2)](ClO(4))(2) (1) complex (AAZ = 6-amino-... more The structure and physicochemistry of the [Ni(II)(AAZ)(2)](ClO(4))(2) (1) complex (AAZ = 6-amino-6-methylperhydro-1,4-diazepine), as a system that is able to mimic some important chelate properties of 1,4,7-triazacyclononane, are reported. The syntheses of a new unsymmetric AAZ-functionalized ligand and the structure of its first heterodinuclear Fe(III)Zn(II) complex are also presented.
Inorganic Chemistry, 2009
The design and development of suitable biomimetic catalytic systems capable of mimicking the func... more The design and development of suitable biomimetic catalytic systems capable of mimicking the functional properties of enzymes continues to be a challenge for bioinorganic chemists. In this study, we report on the synthesis, X-ray structures, and physicochemical characterization of the novel isostructural [Fe III Co II (BPBPMP)(μ-OAc) 2 ]ClO 4 (1) and [Ga III Co II (BPBPMP)(μ-OAc) 2 ]ClO 4 (2) complexes with the unsymmetrical dinucleating ligand H 2 BPBPMP (2-bis[{(2-pyridyl-methyl)-aminomethyl}-6-{(2-hydroxy-benzyl)-(2-pyridyl-methyl)}-aminomethyl]-4-methylphenol).
Chemical Communications, 2010
A new iron(II) complex was synthesized and its photonuclease activity against plasmid DNA was eva... more A new iron(II) complex was synthesized and its photonuclease activity against plasmid DNA was evaluated. After kinetic experiments a k cat of 18.86 AE 2.9 h À1 was obtained, one of the highest nuclease activities of synthetic metallonucleases, selectively activated by 365 nm UV light. This journal is c The Royal Society of Chemistry 2010 Chem. Commun., 2010, 46, 3375-3377 | 3375 COMMUNICATION www.rsc.org/chemcomm | ChemComm a Catalytic constant (i.e. V max at saturation level). b Catalytic efficiency. c Rate enhancement compared to uncatalyzed cleavage of double-stranded DNA (k unc = 3.6 Â 10 À8 h À1 ). d Supercoiled DNA half-life time (t1 2 = Àln(0.5)/k cat ).
Journal of Inorganic Biochemistry, 2011
In this work we report on the synthesis, crystal structure, and physicochemical characterization ... more In this work we report on the synthesis, crystal structure, and physicochemical characterization of the novel dinuclear [Fe(III)Cd(II)(L)(μ-OAc)(2)]ClO(4)·0.5H(2)O (1) complex containing the unsymmetrical ligand H(2)L=2-bis[{(2-pyridyl-methyl)-aminomethyl}-6-{(2-hydroxy-benzyl)-(2-pyridyl-methyl)}-aminomethyl]-4-methylphenol. Also, with this ligand, the tetranuclear [Fe(2)(III)Hg(2)(II)(L)(2)(OH)(2)](ClO(4))(2)·2CH(3)OH (2) and [Fe(III)Hg(II)(L)(μ-CO(3))Fe(III)Hg(II)(L)](ClO(4))(2)·H(2)O (3) complexes were synthesized and fully characterized. It is demonstrated that the precursor [Fe(III)(2)Hg(II)(2)(L)(2)(OH)(2)](ClO(4))(2)·2CH(3)OH (2) can be converted to (3) by the fixation of atmospheric CO(2) since the crystal structure of the tetranuclear organometallic complex [Fe(III)Hg(II)(L)(μ-CO(3))Fe(III)Hg(II)(L)](ClO(4))(2)·H(2)O (3) with an unprecedented {Fe(III)(μ-O(phenoxo))(2)(μ-CO(3))Fe(III)} core was obtained through X-ray crystallography. In the reaction 2→3 a nucleophilic attack of a Fe(III)-bound hydroxo group on the CO(2) molecule is proposed. In addition, it is also demonstrated that complex (3) can regenerate complex (2) in aqueous/MeOH/NaOH solution. Magnetochemical studies reveal that the Fe(III) centers in 3 are antiferromagnetically coupled (J=-7.2cm(-1)) and that the Fe(III)-OR-Fe(III) angle has no noticeable influence in the exchange coupling. Phosphatase-like activity studies in the hydrolysis of the model substrate bis(2,4-dinitrophenyl) phosphate (2,4-bdnpp) by 1 and 2 show Michaelis-Menten behavior with 1 being ~2.5 times more active than 2. In combination with k(H)/k(D) isotope effects, the kinetic studies suggest a mechanism in which a terminal Fe(III)-bound hydroxide is the hydrolysis-initiating nucleophilic catalyst for 1 and 2. Based on the crystal structures of 1 and 3, it is assumed that the relatively long Fe(III···)Hg(II) distance could be responsible for the lower catalytic effectiveness of 2.
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Papers by Fernando Xavier